Frequently Asked Questions




I've got a small ceramic disk capacitor, how can I tell it's value?

The first row will have a number like 33J, 104Z or 223Z, where first two digits denote significant figures; the last digit denotes the multiplier of 10 in pF. The letter denotes the tolerance, for which you should check the product data sheet. If there is a second row this will be the Manufacturer's Identification.
Examples:
33J = 33 x 100 pF = 33pF
104Z = 10 x 104 pF = 0.1μF
223Z = 22 x 103 pF = 22nF

What are the colour bands on a resistor?

Many resistors have 4 bands:
  • The first band gives the first digit.
  • The second band gives the second digit.
  • The third band indicates the multiplier (number of zeros).
  • The fourth band shows the tolerance of the resistor value
  • Silver ±10%, Gold ±5%, Red ±2%, Brown ±1%
  • Green ±0.5%, Blue ±0.25%, Violet ±0.1%, Grey ±0.05%

It's also common to find 5 Band resistors that will have 3 digits before the multiplier and tolerance, whereas a 6th Band show a temperature co-efficient.

eg. Brown Green Red Gold = 15 x 102 = 1500Ω also written 1K5

When we write 1K5 the K in the middle means thousand and replaces a decimal point that might be missed. Similarly we can use R and M for other factors, where 2R2 would be 2.2Ω and 5M6 would be 5.6MΩ or 5.6 x 106.
Colour
Black
Brown
Red
Orange
Yellow
Green
Blue
Violet
Grey
White
Number
0
1
2
3
4
5
6
7
8
9

How do compare different torque units?

There are a variety of units used, most common is Nm (Newton meters) but with small values you might see Nmm (Newton millimetres). This is relatively straight forward as there is a factor of 1000 between the two (1m = 1000mm), unfortunately other measures are also common but all are based on distance x force so conversions are not difficult.
in.oz
lb.ft
kg.cm
g.cm
N.m
in.oz
1
0.00521
0.072
72
0.00706
lb.ft
192
1
13.8
13800
1.36
kg.cm
13.9
0.0723
1
1000
0.0981
g.cm
0.0139
0.0000723
0.001
1
0.0000981
Nm
142
0.738
10.2
10200
1
In the case of in.oz (inch ounce) or kg.cm (kilogram centimetre) they are often depicted at in.ozf or kgf.cm to show a measure of force rather than mass.

What about other Frequently Asked Questions?

John Piccirillo's Robotics miniFAQ for Beginners can be found here as a PDF, updated Aug 2006.
The Robot Competition FAQ can be found here, and contains contains brief summaries of regular robot competitions around the world.


ReferenceMaterial
There are no comments on this page.
Valid XHTML :: Valid CSS: :: Powered by WikkaWiki :: Copyright © 2005 - 2012 MiniSumo.org.uk